Saturday, August 2, 2014

Hello Friends...Today I am going to discuss about the operation of IP data networks and basics of networks. I hope this post will help you.

Recognize the purpose and functions of various network devices such as routers, switches, bridges and hubs.

Select the components required to meet a given network specification

Identify common applications and their impact on the network

Describe the purpose and basic operation of the protocols in the OSI and TCP/IP models

Predict the data flow between two hosts across a network

Identify the appropriate media, cables, ports, and connectors to
connect Cisco network devices to other network devices and hosts in a
LAN.-----------------------------------------------------------------------------------------------------------------------

Network Devices:

HUB:

Networks using a Star topology require a central point
for the devices to connect. Originally this device was called a
concentrator since it consolidated the cable runs from all network
devices. The basic form of concentrator is the hub.
As
shown in Figure; the hub is a hardware device that contains multiple,
independent ports that match the cable type of the network. Most common
hubs interconnect Category 3 or 5 twisted-pair cable with RJ-45 ends,
although Coax BNC and Fiber Optic BNC hubs also exist. The hub is
considered the least common denominator in device concentrators. Hubs
offer an inexpensive option for transporting data between devices, but
hubs don't offer any form of intelligence. Hubs can be active or
passive.
An active hub strengthens and regenerates the incoming signals before sending the data on to its destination. Passive hubs do nothing with the signal.

Switches:

Switches are a special type of hub that offers an additional layer of
intelligence to basic, physical-layer repeater hubs. A switch must be
able to read the MAC address of each frame it receives. This information
allows switches to repeat incoming data frames only to the computer or
computers to which a frame is addressed. This speeds up the network and
reduces congestion. Switches operate at both the physical layer and the data link layer of the OSI Model.

Routers

Routers Are networking devices used to extend or
segment networks by forwarding packets from one logical network to
another. Routers are most often used in large internetworks that use the
TCP/IP protocol suite and for connecting TCP/IP hosts and local area
networks (LANs) to the Internet using dedicated leased lines.
Routers
work at the network layer (layer 3) of the Open Systems Interconnection
(OSI) reference model for networking to move packets between networks
using their logical addresses (which, in the case of TCP/IP, are the IP
addresses of destination hosts on the network). Because routers operate
at a higher OSI level than bridges do, they have better packet-routing
and filtering capabilities and greater processing power, which results
in routers costing more than bridges.

WAPs (Wireless Access Point)

A wireless network adapter card
with a transceiver sometimes called an access point, broadcasts and
receives signals to and from the surrounding computers and passes back
and forth between the wireless computers and the cabled network.
Access
points act as wireless hubs to link multiple wireless NICs into a
single subnet. Access points also have at least one fixed Ethernet port
to allow the wireless network to be bridged to a traditional wired
Ethernet network.